Electric heater



Original Filed Oct. 25. 1920 Patented Jan. 20, 1925:.

UNITED STATES PATENT OFFICE.

EDWIN N. LIGHTFOOT, OF NEW YORK, N. Y., AND ALVA T. SMITH, OT NEWARK, NEW

JERSEY, ASSIGNORS TO THE CUTLER-HAMMER MFG. 00., OF MILWAUKEE, WIS- CONSIN, A CORPORATION OF WISCONSIN.

EIJECTRIC HEATER.

Application filed October 25, 1920, Serial No. 419,394. Renewed May 30, 1924.

. To all whom it may concern:

Be it known that we, EDWIN N. LIGHT- F001 and ALVA 'l. SMITH. citizens of the United States, residing, respectively, at New York, in the county of Bronx and State of New York, and Newark, in the county of Essex and State of New. Jersey, have invented new and useful Improvements in Electric Heaters, of which the following is a specification.

This invention relates to an electric heater.

The electric heater to which the invention is-particularly applicable comprises in general a tubular jacket or casing, a terminal fastened to each end thereof, a re sistor arranged within the jacket andconnected to the terminals, and insulation between the resistor and the jacket.

An object of the invention is to provide an improved method or process of making electric heaters.

Another object is to provide an improved method of insulating the resistor of an electric heater.

Another object is to provide an improved method of assembling an electric heater.

Another object is to provide an improved method or process of introducing the insulation into the electric heater.

Other objects and advantages will hereinafter ap ear.

The views of the drawings are:

Figure 1 shows a resistor arranged in a 5 helix;

Figure 2 is a vertical longitudinal section through several beads of insulation;

Figure 3 shows the beads arranged on the helical resistor;

helical resistor arranged therein;

Figure 5 shows the jacket with terminals at each end connected with the beaded helical resistor; and

Figure 6 shows the completed electric heater after the jacket has been contracted to change the form of and to compact the insulation.

. The method in general consists of introducing, between the resistor and the jacket, insulation in one form and thereafter subjectin the same to pressure to change the form t ereof, and compressing and compact- Figure 4 shows a jacket with. the beaded ing such insulation in the jacket and around and about the resistor.

The insulating material in powdered or granular form is mixed with a suitable binder and moulded into tubular beads 1 such as are shown in Figure 2. Kaolin or clay is a suitable binder and works well when used in the proportion of one part of kaolin to about 15 to 20 parts of insulating material.

The beads may be moulded by compression, or may be extruded and cut into the desired lengths. Beads of from three-sixteenths of an inch to one inch in length are particularly suitable to small diameter heaters.

, After being formed, the beads are allowed to dry.

The amount of binder employed is su'fii cient and the treatment during and after formation of the beads is such as to make a bead that will withstand, without breaking, handling during the process of assembling the electric heaters, but will .not be too resistant to manipulation as will prevent the ready breaking thereof into granular or powdered form prior to being tightly compacted within the jacket of the electric heater and around and about the resistor.

The inner diameter of the tubular beads is made just large enough so that the beads will slide easily along the helical resistor, while the outside diameter is such that the beaded resistor will slide easily into the jacket.

Of course for resistors and jackets of different diameters, beads of suitable inside and outside diameters must be used. k

When making an electric heater. beads l of insulation of suitable inside and outside diameter are strung on the resistor 2.

The beaded resistor is then drawn into the jacket 3.

The terminals 4. may then be rigidly fastened to the ends of the jacket 3 and the ends of the resistor 2 fastened to theterminals. I

This fastening of the terminals to the jacket and the resistor to the terminals may be accomplished in the manner set forth in Patent No. 1,359,400, granted November 16, 1920, to Edwin N. Lightfoot.

The shape and size of the relatively large pieces of insulation may vary and they may take forms other than tubular beads.

insulation is changed under pressure, thus insuring thatthe insulation is uniformly and tightly compacted around and about the resistor.

After the heater is assembled and the terminals fastened thereto, the jacket is finally swaged or otherwise contracted crosswise to break up the beads of insulation into granules or powder and to compress and com: pact the insulation in the jacket and around and about the resistor. F i ure 6 illustrates how the insulation fills al space around and about the resistor. The insulation insulates the resistor from the jacket and its turns from each other. It further holds the resistor and its terminal in place so that the heater may be bent into various forms.

An insulating bushing 5 formed to cover the end of the sleeve 6, which insulates the plug terminal from the jacket, and to engage the jacket may be threaded upon the plug terminalr This bushing protects the insulating sleeve and further insulates the plug terminal from the jacket.

The described process of assembling an electric heater and insulating the resistor from the jacket, insures that sufficient insulation is introduced into the jacket to thoroughly and uniformly insulate the resistor and fill all space around and about the'resisto-r, for a known amount of insulation is thus introduced. Furthermore,

,the operator can at all times see the insulation which is bein introduced, thereby reducing the possibility of introducing less than the proper amount which may be predetermined.

A further advantage of this process of assembling an electric heater is that no complicated machinery is required.

The invention. contained herein is, of

course, susceptible of other embodiments and adaptations.

The invention claimed is:

1. The method of making an electric heater having a resistor enclosed by and insulated from a tubular jacketwhich comthe same in the prises surrounding theresistor with beads of insulation, placing the beaded resistor within the jacket, and reducing the beads to powder and compressing and compacting jacket and around and about the resistor.

2. The method of making an. electric heaterhaving a resistor enclosed by and insulated from a tubular jacket which comprises surrounding the resistor with beads of insulation, placingthe beaded resistor within the jacket, and subjecting the beads to pressure to reduce the same to powdered insulation.

3. The method of making an electric heater having a resistor enclosed by and insulated from a tubular jacket which comprises surrounding the resistor with beads of insulation, placing the beaded resistor within the jacket, and contracting the jacket to reduce the beads to granular form and to compress and compact the same around and about the resistor.

4. The method of assembling an electric heater having a resistor enclosed by and insulated from an elongated tubular jacket which comprises surrounding the resistor with beads of insulatiomplacing the beaded resistor within a tubular jacket with the beads arranged along the axis of the jacket,

and rigidly fastening terminals to the ends of the jacket.

5. In the production of heaters having a helical resistor element located within an elongated jacket and insulated therefrom by compacted comminuted insulating material, the process of positioning and holding the resistor element within the jacket during compacting of the insulating material, which comprises introducing the insulating material within the jacket in the form of coherent masses of appreciable size and in a relation to space the resistor from the acket, and utilizing certain of such masses of insulating material for positioning and holding the resistor element with reference to the jacket during subsequent treatment.

6. The method of insulating the resistor of an electric heater from the enclosing jacket thereof which comprises surrounding the resistor with beads of insulation, breakingup the beads into granular insulation,

'the resistor-from the jacket by relatively large pieces of insulation, and subsequently reducing the pieces to granular form.

8. The method of insulating the resistor of an electric heater fronr the enclosing jacket thereof which comprises separating the resistor from the'jacket by relatively large pieces of insulation, and subsequently subjecting the pieces of insulation to pressure thereby reducing the size thereof and compressingand compacting the same in the jacket and around and about the resistor.

9. In the production of heaters having a helical resistor element located within a jacket and insulated tllGIOiIOIIl by com- 'pacted connninuted insulating material, the

process of positioning and holding the reslstor element Within thejacket during comparting of the insulating material, which -omprises introducing the insulating material within the jacket in the form of coherent masses of appreciable size and in a relation to space the resistor from the jacket, and

thereafter comminuting the insulating material and compacting the same.

10. The method of insulating the resistor of an electric heater from the enclosing 1 jacket thereof which comprises separating the resistor from the jacket with insulation held together in definite predetermined quantities by a temporary binder, and subsequently subjecting such temporarily bound EDWIN N. LIGHTFOOT. ALVA T. SMITH. 

